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Performance and Tuning Guide Volumes 1 - 3 (Online Only) |
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| Chapter 19 Adaptive Server Optimizer |
Chapter 19
This chapter introduces the Adaptive Server query optimizer and explains the steps performed when you run queries.
This chapter explains how costs for individual query clauses are determined.
Chapter 22, "Access Methods and Query Costing for Single Tables,"explains how these costs are used to estimate the logical, physical, and total I/O cost for single table queries.
Chapter 23, "Accessing Methods and Costing for Joins and Subqueries," explains how costs are used when queries join two or more tables, or when queries include subqueries.
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| Definition |
| Steps in query processing |
| Working with the optimizer |
| Object sizes are important to query tuning |
| Query optimization |
| Factors examined during optimization |
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| Preprocessing can add clauses for optimizing |
| Converting clauses to search argument equivalents |
| Converting expressions into search arguments |
| Search argument transitive closure |
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| Join transitive closure |
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| Predicate transformation and factoring |
| Guidelines for creating search arguments |
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| Search arguments and useful indexes |
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| Search argument syntax |
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| How statistics are used for SARGS |
| Using statistics on multiple search arguments |
| Default values for search arguments |
| SARGs using variables and parameters |
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| Join syntax and join processing |
| How joins are processed |
| When statistics are not available for joins |
| Density values and joins |
| Multiple column joins |
| Search arguments and joins on a table |
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| Datatype mismatches and query optimization |
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| Overview of the datatype hierarchy and index issues |
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| Datatypes for parameters and variables used as SARGs |
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| Compatible datatypes for join columns |
| Suggestions on datatypes and comparisons |
| Forcing a conversion to the other side of a join |
| Splitting stored procedures to improve costing |
| Basic units of costing |
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